The present invention relates to an electrostatic image-developing toner which is used for an electronograph and the like.
A developer to be used for an electronograph and the like is once adhered onto an image carrier, for example, such as a photosensitive material on which electrostatic images are formed, then transferred from the photosensitive material onto a paper in the transfer step, and then fixed onto a copy paper in the fixing step. In this case, as developers for developing electrostatic images formed on the latent image carrying surface, there have been known a dual-component developer comprising a carrier and a toner and a monocomponent developer requiring no carrier.
By the way, charging property is one of important properties required for the toner, and the formation of positive or negative charge having a proper level and the general stability of the charge level in the lapse of time are required even under its continuous use or under an adverse condition.
Previously, toners have been made in general by melting a binder resin and additives such as a charge-controlling agent with heat, admixing, pulverizing after cooling, and classifying. They have been also made by mixing a monomer and additives such as a charge-controlling agent and polymerizing the same.
However, toners produced by such methods show bad dispersibility of a charge-controlling agent, less charge stability and unstable print density when printed under an adverse condition during their continuous use. Also, to be present the charge-controlling agent on the surface of toner, which governs the charging property, it has been necessary to add a large amount of charge-controlling agent.